Various contact springs are already established in the market. According to one embodiment, it is a coiled compression spring. It builds up the contact force in the axial direction between a contact bearing on the fixation axis and a counter bearing in the housing. This design has the particular disadvantage that the spring covers the entire threaded area of the fixation, i.e., typically approximately 2 mm. The spring produces an electrical contact in all positions. The length of the compressed spring must also be added to the length of the head. If the head additionally receives a seal, the length thereof must also be added thereto. An electrode head having this type of spring is therefore too long for many applications.
In another version, the contact force is built up radially between the shaft and the housing, which is known from U.S. Publication No. 2007/0055335, for example. A coiled spring for the electrical connection between the electrode housing and the shaft is disclosed therein, which is implemented as an essentially level coiled spring revolving around the shaft under spring tension, and which has sliding contact with the housing and/or the shaft at its leg ends while exerting a radially oriented spring force. A contact spring of this construction has the problem that the radial contact force acts on one side on the shaft of the fixation. The shaft requires a radial counter bearing on which friction can occur. This friction increases the number of turns to unscrew the fixation from the electrode head.
The present inventive disclosure is directed toward overcoming one or more of the above-identified problems.
An object is therefore to avoid the problems of the cited prior art and to provide a contact spring which has the smallest possible axial extension, and in which one sided radial forces do not occur or are at least compensated for, as well as an electrode line, which has the smallest possible electrode head and the longest possible flexible section.
An object is achieved by features of the independent claim(s). Favorable embodiments and advantages of the present invention will be apparent from the further claims and the description.